The present invention relates to a two-legged walking transportation device for a person to ride on and thereby walk.
Conventionally, there are riding-style two-legged walking transportation devices, one example of which is described in Patent Document 1. As shown in FIG. 7, the two-legged walking transportation device 100 includes an upper body unit 101 provided with a seat on which a person (hereinafter, a “rider”) rides, and a pair of right and left leg units 102R and 102L for supporting the upper body unit 101. Each of the leg units 102R and 102L includes a thigh link 106 connected to the upper body unit 101 via a hip joint 103 with three degrees of freedom, a lower leg link 107 connected to the end of the thigh link 106 via a knee joint 104 with a single degree of freedom, a plate-like foot portion 108 connected to the end of the lower leg link 107 via an ankle joint 105 with two degrees of freedom, and a foot rest 109 fixed slightly above the ankle joint 105.
The rider rides on the two-legged walking transportation device 100 by sitting on the seat of the upper body unit 101 with the feet on the foot rests 109. In addition, upon riding, the rider has his/her thighs, knees, and lower legs free (unbound), as shown in FIG. 7.
Accordingly, the two-legged walking transportation device 100 can omit adjustments of knee joint positions to be made in accordance with the rider's body shape. In addition, the two-legged walking transportation device 100 keeps the rider's barycentric position low, making it possible to readily control balancing and, if it falls, alleviate the impact on the rider.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-319940
Incidentally, in general, to achieve two-legged walking, two functions, “gait generation” and “balance maintenance”, are important. Here, the gait generation function is a function for planning a route from the current position to a destination and movement of the right and left legs or feet to walk along the route. The balance maintenance function is a function for preventing falling during a halt or two-legged walk.
Of the two functions, the balance maintenance function can be relatively readily achieved based on information from sensors or suchlike disposed on the soles (treads) of the two-legged walking transportation device.
However, to realize the gait generation function, high judgment ability is required in terms of, for example, understanding of the purpose of gait and comprehension of environmental information, and therefore it is difficult for the current technology to enable the realization. For example, in the case where there is unknown irregular ground to walk on or there are unknown obstacles on the way to the destination, it is necessary to consider, for example, whether such a case could hinder walking or whether or not to bypass the route, and if so, which route should be taken, and therefore it is extremely difficult for a computer to make accurate and quick judgments. Moreover, to obtain information to be the basis for the judgments, a number of high-precision sensors are required, and therefore at present, no realistic solution is available.
In relation to this, the conventional two-legged walking transportation device 100 shown in FIG. 7 is a mechanism on the premise that both the gait generation function and the balance maintenance function are realized under automatic control of a computer, and therefore it is difficult for the two-legged walking transportation device 100 to robustly walk with two legs in an unknown environment (e.g., irregular ground).
Furthermore, conventionally, there are two-legged walking transportation devices of the type that includes a means for the rider to provide some instruction, such as a joystick. The means of instruction allows the rider to provide a trigger to take the next step or an instruction to take a simple action such as moving forward/backward or circling, within the range of a previously created gait plan. However, for the two-legged walking transportation devices of this type also, the rider cannot provide instructions to take complicated actions, such as walking on irregular ground while successfully avoiding or tramping on obstacles by adjusting fine movement and strength of the legs, e.g., strides and the strength of stepping, and naturally, robust walking with two legs is not possible in any unknown environment.
The present invention has been made in view of circumstances as mentioned above, and an objective thereof is to provide a riding-style two-legged walking transportation device capable of robustly walking with two legs even in an unknown environment such as irregular ground.